From 13a79a4741d37fda2fbafb953f0f301dc007928f Mon Sep 17 00:00:00 2001 From: Yongqiang Yang <xiaoqiangnk@gmail.com> Date: Tue, 13 Dec 2011 21:51:55 -0500 Subject: [PATCH] ext4: avoid potential hang in mpage_submit_io() when blocksize < pagesize If there is an unwritten but clean buffer in a page and there is a dirty buffer after the buffer, then mpage_submit_io does not write the dirty buffer out. As a result, da_writepages loops forever. This patch fixes the problem by checking dirty flag. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org --- fs/ext4/inode.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b5edc6e4bab9..cf20e1fe7782 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1339,8 +1339,11 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd, clear_buffer_unwritten(bh); } - /* skip page if block allocation undone */ - if (buffer_delay(bh) || buffer_unwritten(bh)) + /* + * skip page if block allocation undone and + * block is dirty + */ + if (ext4_bh_delay_or_unwritten(NULL, bh)) skip_page = 1; bh = bh->b_this_page; block_start += bh->b_size;